I like the idea of decentralized social media. Having a single for-profit company moderating all content feels sleazy.
The beauty of the fediverse is that there's independent competition. If you don't like how a certain space is being run, you can choose another or create your own. It's ironically very "free-market capitalistic", in contrast to the political leanings of the user-base. Lol
It's so easy to switch from one instance to another (in fact many people advocate having alternate accounts on multiple servers as a rule). Anyone can start a community and truly moderate it how they choose, or choose a server with the rules that they choose. It's not surprising that the Federverse has succeeded in creating spaces that are much more healthy, especially for vulnerable people. It is impressive how stark that difference is; harassment and abuse are accepted as given on just about every corporate media, with very little recourse.
I'm probably going to explain it poorly, because I'm not a computer science person, but the fediverse is the umbrella term for the all the independent and interconnected servers using the same protocol to communicate and build federated social media. Meaning it's not centrally controlled, like we're a bunch of ships at sea tied together instead of all using the same port owned by one entity (like reddit).
So, Lemmy and a few others for something reddit-style, Mastodon for something twitter style, and so on. All would fall under the umbrella of the "fediverse".
As for getting involved, you could try to add content to attract people here and entertain those who already are (that's what I've been doing), or if you're tech-savvy, you could even create your own federated instance.